Colposcopic transformation zone 3 means that the transformation zone extends partially into the cervical canal or is entirely within the cervical canal, and that the entire transformation zone and lesion cannot be seen with the aid of an adjunct, or that the entire transformation zone and lesion cannot be seen. The transformation zone is the area between the squamous and columnar epithelium of the cervix. The first step in colposcopy is to distinguish whether the old and new squamous-column junction (SCJ) or transformation zone is completely visible, and then to identify whether the signs of colposcopy are normal. If there is abnormality, judgment is made to analyze the severity and extent of the lesion, and biopsies are taken for pathological examination. The transformation zone is categorized into 1, 2 and 3 types. Type 1 transformation zone is that all transformation zones are visible and all lesion borders are visible; type 2 transformation zone is that part of the transformation zone extends into the cervical canal, but the upper border of the transformation zone and the upper border of the lesion can still be seen with the help of auxiliary tools; type 3 transformation zone is that the transformation zone partially extends into the cervical canal or is completely located in the cervical canal, and all transformation zones and lesions can’t be seen with the help of auxiliary tools, or all transformation zones and lesions can’t be seen. Type 3 transformation zone is that the whole transformation zone and lesion cannot be seen with the aid of auxiliary tools, or cannot be seen. Colposcopy requires a professional gynecologist, and it is recommended to go to a regular hospital for treatment.